Donor Time to Death and Kidney Transplant Outcomes in the Setting of a 3-Hour Minimum Wait Policy

Importance: Lengthening waiting lists for organ transplantation mandate development of strategies to expand the deceased donor pool. Due to concerns regarding organ viability, most organ donation organisations internationally “stand-down” from potential circulatory death donors (DCD) after 1-2 hours, possibly underutilising an important organ source. UK policy mandates a minimum 3-hour stand-down time. Objective: To determine whether time to death (TTD, also termed “agonal time”) from withdrawal of life-sustaining-treatment (WLST) is an important predictor of kidney transplant outcome. Design: Population-cohort study from 2013-2021 with follow-up until October 2023. Setting: All 23 UK kidney transplant centres, using data from the prospectively maintained UK Transplant Registry. Participants: Adult recipients of DCD kidney-alone transplants. Exposure: Duration of TTD defined as time from WLST to donor mechanical asystole. Main outcomes and measures: Primary outcome was 12-month eGFR, with secondary outcomes of delayed graft function and graft survival (censored at death or 5 years). Results: This study included 7,183 kidney transplant recipients (65% male). Median (IQR) donor and recipient age was 55 (44-63) and 56 (47-64) years. TTD median (range) was 15 (0-407) minutes, with 885 and 303 kidneys transplanted from donors with TTD over 1 and 2 hours respectively. Donor TTD was not associated with recipient 12-month eGFR on adjusted linear regression (change per doubling of TTD = -0.25, 95% CI -0.68 to 0.19, P=0.27), nor with delayed graft function (aOR=1.01; 95% CI 0.97-1.06, P=0.65) or graft survival (aHR=1.00; 95% CI, 0.95-1.07, P=0.92). These findings were confirmed with restricted cubic spline models (assessing non-linear relationships) and tests of interaction (including normothermic regional perfusion, donor age, ischemic times). In contrast, donor asystolic time, cold ischemic time, and reperfusion time were independent predictors of outcome. Compared to theoretical 1- or 2-hour stand-down times, UK policy (minimum 3-hour wait to stand-down) has led to 14.1% and 4.4% more DCD transplants, respectively. Conclusions and relevance: In this cohort study of DCD kidney recipients, donor TTD did not impact on post-transplant outcome, in contrast to subsequent ischemic times. Altering international transplant practice to mandate minimum 3-hour donor stand-down times would substantially increase numbers of kidney transplants performed without prejudicing outcomes

Evaluating image quality in surgical photography: a multivariable analysis of cameras and shooting conditions

\ua9 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Introduction: Use of mobile devices with high-quality cameras has expanded medical photography. We investigate the impact of different devices and conditions on photograph quality in a surgical setting. Methods: Fourteen surgeons across six centres scored photograph quality of kidneys donated for transplantation. Images were captured using an iPhone, iPad, or DSLR camera on automatic modes under varying lighting conditions. In blinded A/B testing, surgeons selected the image perceived more clinically useful for remote organ quality assessment and rated each on a 5-point Likert scale. Quality was objectively analysed using two computer vision referenceless quality assessment tools (BRISQUE & NIMA). Results: Of 369 photographs, mobile device images were rated higher quality by surgeons (78.4%) compared to DSLR (9.4%, p < 0.001). Multilevel regression using BRISQUE showed higher quality for iPhones (β = −5.86, p < 0.001) and iPads (β = −3.90, p < 0.001) versus DSLR. Room lighting improved quality over direct overhead illumination with theatre lights (β = 17.87, p < 0.001). Inter-rater (Gwet AC = 0.78) and intra-rater (Cohen’s κ = 0.86) agreements were high. Discussion: Smartphones can produce high quality photographs. These findings should reassure clinicians that smartphone devices do not compromise photograph quality and support their use in clinical practice and image analysis research

Sensitivity of the acoustic scattering problem in prolate spheroidal geometry with respect to wavenumber and shape

The sensitivity of analytical solutions of the direct acoustic scattering problem in prolate spheroidal geometry on the wavenumher and shape, is extensively investigated in this work. Using the well known Vekua transformation and the complete set of radiating "outwards" elgensolutions of the Helmholtz equation, introduced in our previous work ([Charalambopoulos and Dassios (2002)],[Gergidis, Kourounis, Mavratzas, and Charalambopoulos (2007)]), the scattered field is expanded in terms of it, detouring so the standard spheroidal wave functions along with their inherent numerical deficiencies. An approach is employed for the determination of the expansion coefficients, which is optimal in the sense, that minimizes the L-2 norm of the error related to the satisfaction of the boundary condition on the surface of the scatterer. The study of the conditioning of the matrices involved in the linear systems, the solution of which provides the expansion coefficients, reveals the need for implication of numerical implementations using arbitrary precision arithmetics. Numerical and convergence properties estimations such as condition numbers, L-2 and L-infinity error norms prove the robustness of the adopted methodology. A study of the dependence of the error with respect to geometrical, physical and numerical parameters is developed. Three dimensional representation of the L-2 norm clarifies the distribution of errors on the scatterer's surface.Cmes-Computer Modeling in Engineering & Science

Sensitivity of the Acoustic Scattering Problem in Prolate Spheroidal Geometry with Respect to Wavenumber and Shape

The sensitivity of analytical solutions of the direct acoustic scattering problem in prolate spheroidal geometry on the wavenumber and shape, is extensively investigated in this work. Using the well known Vekua transformation and the complete set of radiating "outwards'' eigensolutions of the Helmholtz equation, introduced in our previous work ([Charalambopoulos and Dassios(2002)], [Gergidis, Kourounis, Mavratzas, and Charalambopoulos (2007)]), the scattered field is expanded in terms of it, detouring so the standard spheroidal wave functions along with their inherent numerical deficiencies. An approach is employed for the determination of the expansion coefficients, which is optimal in the sense, that minimizes the L2 norm of the error related to the satisfaction of the boundary condition on the surface of the scatterer. The study of the conditioning of the matrices involved in the linear systems, the solution of which provides the expansion coefficients, reveals the need for implication of numerical implementations using arbitrary precision arithmetics. Numerical and convergence properties estimations such as condition numbers, L2 and L∞ error norms prove the robustness of the adopted methodology. A study of the dependence of the error with respect to geometrical, physical and numerical parameters is developed. Three dimensional representation of the L2 norm clarifies the distribution of errors on the scatterer's surface